function Enemy(src,w,h,x,y){
    Sprite.call(this,src,w,h,x,y)
}
Enemy.prototype = new Sprite;


Enemy.prototype.move = function(speed){
  this.imgNode.style.top = this.imgNode.offsetTop + speed + 'px'
  this.y = this.imgNode.offsetTop;
}

Enemy.prototype.die = function(){

    this.imgNode.src = 'img/wsparticle_07.png';
    var that = this;
    (function(node){
      setTimeout(function(){
          node.parentNode.removeChild(node)
      },200)
    })(that.imgNode)
}
